//alert("我也不知道讲的啥")
//console.log("控制台输出");	
////定义变量
//	var r = 6;
//	console.log(r);
//
////定义常量-常量不可以被赋值，且常量名全部都要大写
//	const CE = 3;
//	console.log(CE);

//
////js的数据类型
//var num = 23;
//var t = "小明";
//var u = true;  //成立
//var f = false;  //不成立
//var s = undefined;  
//var i = {};
////console.log(num);
////console.log(t);
////console.log(u);
////console.log(s);
////console.log(i);
//
//
////正数和负数
//var num1 = 12;
//var num2 = -13;
//
////数值型
//var oct = 032;  //八进制
//var dec = 26;  //标准格式
//var hex = 0x1a;  //
//var funm1 = 7.26;  //标准格式
//var funm2 = -6.24;  //标准格式
//var funm3 = 3.14E6;  //E后面是x10x6？？
//var funm4 = 8.96E-3;  //E后面是x0.1x3??
//
//
////字符串里面放引号- 双引号嵌套单引号，单引号嵌套双引号
//var name1 = "小明'和'小红";
//var name2 = '小红"和"小明';
//console.log(name1);
//console.log(name2);
//
////一次性定义多个变量（不推荐这么写）
//var num = '', total = "";
////换成下面这种写法
//var num = '';
//var total = "";
//
//
////转义字符
//var name3 = "小明\"和\"小红";
//var name4 = '小明\'和\'小红';
//
//
////转行的转义字符
//var name5 = "小明\n和\n小红";
//console.log(name5);
//

//var n1 = prompt("你开心就好");
//var n2 = prompt("嗯哼");


////把类型转成数字类型的
//
//n1 = parseInt(n1);
//n2 = parseInt(n2);
////
////console.log(n1 + n2);


//var n1 = "10";
////console.log(n1);
//////为什么要从字符串类型，转成数字类型
////console.log(parseInt(n1));
//console.log(Number(n1));
////console.log(parseFloat(n1));
//
//var n2 = 20;
//console.log(n2);
//console.log(String(n2));
//
//
//var u = undefined;
//console.log(isNaN(u));
//console.log(isNaN(n1));

//根据圆的半径
var p = Math.PI;
//var p = 3.14;
console.log(p);
var a = prompt('请输入半径'); //半径
document.querySelector("#a").value = a;
document.querySelector("#b").value = (a * 2 * p);
document.querySelector("#c").value = (Math.pow(a,2) * p);

var d = a * 2;
//console.log('圆的面积是：' + Math.pow(a,2) * p);
document.querySelector("#d").value = d;
document.querySelector("#e").value = (d * p);
document.querySelector("#f").value = (Math.pow(d / 2,2) * p);